1. Field of the Invention
The present invention relates to a projection apparatus, and more particularly, to a projection apparatus with a single light valve.
2. Description of the Prior Art
With the progress of science and technology, projection apparatuses gradually play an important role in use of family, entertainment or business. Recently, requirements of large size flat displays greatly grow up, and desires of consumers for image size and image quality are becoming stricter and stricter. The related projection technology is accordingly advanced. The technology of the projection apparatus is to project an image onto a screen through an optical projection method and to enlarge the image size through an optical method. Accordingly, the bottleneck in the size of the flat display could be broken, and the main body of the projection apparatus could become thinner and lighter.
The projection apparatus according to the prior art is composed of a light engine system, a light valve, and a projection lens. The light valve has a plurality of pixel units, and the light engine system could be composed of a light source and an illumination lens module. A light beam generated from the light source could be projected onto the light valve through the illumination lens module, and be transferred to have an image signal through the light valve. After that, the light beam with image could be projected onto a screen by the projection lens, and the image could be displayed.
However, based on the consideration of maximizing the energy of the light beam, reducing interference between light beam and optimizing the image quality, the illumination lens module configured to project the light beam from the light source on the light valve has a lot of lenses and a specific light path length, so that the size of the projection apparatus is limited in miniaturization. Although the light engine system has been developed to include a reflective mirror disposed therein to reduce the size of the projection apparatus through folding the light path, the reflective mirror is disposed off the optic axis. Thus, the whole projection apparatus has larger unsteadiness, and the reflective mirror increases manufacturing difficulty due to its large size. This method of placing the reflective mirror is not easily accepted by the market.
Therefore, with the development of the projection apparatus toward lightness and thinness, to provide a projection apparatus having an illumination lens module with no reflective mirror is an objective in this field.